1. Field of the Invention
This invention relates to a sheet conveying device for a copier, a printer or the like.
2. Description of the Related Art
In a conventional sheet conveying device, as shown in FIG. 12, transmission of the rotating drive force to a roller, such as conveying roller 101 or the like, is from an idler gear 108 to a conveying-roller gear 107, and further to a conveying roller 101.
The conveying-roller gear 107 is mounted on bearing unit 111 of the main body using bearing 110. As shown in FIG. 13, the conveying-roller gear 107 rotates in a counterclockwise direction, and the idler gear 108 rotates in a clockwise direction.
An end portion of the conveying roller 101 is subjected to D-cut, and the drive is transmitted via the D-cut surface.
In the above-described conventional device, however, if conveying roller 101 is overloaded due to jamming or the like, and thus a countervailing a force tending to stop the rotation exists, an immoderate force is applied from the idler gear 108 to the conveying-roller gear 107 in the direction P of the pressure angle of the gear. As a result, as shown in FIG. 13, a force pushing away from bearing unit 111 is applied to the conveying roller 101 in the direction Q, with the following disadvantages:
(1) The toothed surfaces of the gears are damaged. PA1 (2) The conveying roller 101 tries to leave the bearing unit 111 of the main body, thus damaging the bearing unit 111 of the main body. PA1 (3) The drive of a driving motor (not shown) in the main body is stopped.